Do I look like a dictionary?

Last week I was working on Layton's invitations for his upcoming party.
As he hopped up to the table to help me stuff the envelopes he started to read one outloud to me.

Layton: "Mom? What does RSVP stand for?"
Me: [After thinking about it for too long] "Ummm, actually Lay... I don't really know what it 'stands for' but it means -  please call and let us know if you will be able to come to the party."

He then stares at me for a minute with a puzzled look on his face.

Layton: "Yeah mommy, but it says RSVP. What's that part mean?'
Me: "Layton, I don't know how to explain it any better. I don't know what that part stands for - but, when people see that part? They just know that they are supposed to call."

Layton: "But, how do they know that?"
Me: "Um... they just do."
Layton: "Okay, I'm just kinda confused, like you." - This is followed by a laugh.
"Oh I KNOW!! Mom! Why don't we just google it?"
Then he CRACKS up laughing like he is so proud of himself for thinking of that.

Then there is me... just sitting there feeling like a total dumb-ass.

[[Oh, and P.S.]]
R.S.V.P. stands for a French phrase, "répondez, s'il vous plaît," which means "please reply."

... and I am so sure that if I would have known and just gave him that definition when he asked what it meant?
Most likely the kid would still have been just as confused.